A test method and device for simulating formation and breaching of a dam in a narrow and deep valley

Abstract

The application relates to the technical field of dam-break simulation, and discloses a test method and device for simulating formation and dam-break of a dam in a narrow and deep valley, and aims to solve the problems of poor accuracy and large consumption of manpower and material resources in the existing dam-break simulation method, and the scheme mainly comprises the following steps: constructing a test device; controlling a water supply module to form an upstream flow, and providing soil material capable of completely blocking a river channel in a soil material sliding module, and controlling the soil material in the soil material sliding module to slide into a river channel model and accumulate into a dam; after the soil material sliding into the river channel model completely blocks the river channel, obtaining test working condition parameters; determining whether the dam will be dammed under the test working condition parameters, and if yes, simulating the formation and dam-break process of the dam in the narrow and deep valley; and recording image data and test data in the formation and dam-break process of the dam in the narrow and deep valley through a monitoring module. The application improves the accuracy of dam-break simulation and reduces the consumption of manpower and material resources, and is suitable for narrow and deep valleys.

Description

Technical Field

[0001] This application relates to the field of landslide dam failure simulation technology, specifically to a test method and apparatus for simulating the formation and failure of landslide dams in narrow and deep river valleys. Background Technology

[0002] Unlike artificial earth-rock dams, landslide dams are mostly formed by the rapid accumulation of loose, unstable, and heterogeneous deposits. The overall density of the dam body is not high, and the dam structure lacks the seepage prevention, drainage equipment, and slope protection that are common in artificial earth-rock dams. Furthermore, the water level of the upstream landslide dam lake is highly susceptible to fluctuations, making landslide dams extremely prone to instability and failure.

[0003] Because landslide dam failures often occur in high mountain valleys, are sudden, and involve high risks during on-site surveys, making it difficult to observe the entire failure process in real time, current practices primarily involve indoor model tests of landslide dam failures, including mechanistic studies and efficacy demonstrations. While existing indoor landslide dam failure simulation tests are relatively mature, two problems remain: First, researchers often conduct tests by pre-assembling the dam body, which fails to accurately recreate the landslide dam formation scenario and does not match actual field conditions. Second, existing landslide dam failure simulation tests are conducted in regular glass flumes and river channels, neglecting the characteristic of landslide dams often occurring in narrow and deep river channels. This leads to the neglect of the impact of narrow and deep terrain on breach development (especially widening) and the selection of control measures when studying breach mechanisms and site-specific control measures. For example, when the ratio of the vertical breach depth to the dam height is less than 1 / 2, the impact of narrow and deep river channels on breach widening is relatively small and can be disregarded. However, the collapse of a landslide dam is a process of gradual erosion and collapse. When the dam body near the dam axis is almost vertically eroded to the bottom, leaving only a very low dam section at the breach entrance, the narrow and deep river channel has a limiting effect on the lateral widening of the breach, which cannot be ignored. Furthermore, the framework of a landslide dam formed by sliding down a sloping, unweathered bank at a low level is mainly composed of coarse particles, while the framework of a landslide dam formed by sliding up a severely weathered, uphill bank is mainly composed of fine particles. Different landslide heights, material compositions, and the geometry of the naturally stacked dam body all affect whether the dam will collapse. Unlike artificial earth-rock dams, the upstream and downstream slopes of a landslide dam are mainly gentle slopes. If this characteristic is fully considered in the experiment, it is possible for the dam not to collapse. However, dam break tests are mostly large-scale tests, involving several screening, stacking and cleaning of dam break materials, which require extremely high manpower and material resources. If parameters such as upstream flow, material composition and geometric characteristics are not set properly to avoid factors affecting dam breakage, the dam body may not break after the top overflow, resulting in test failure. In this case, it is difficult to measure the required dam breakage parameters, and a lot of manpower and material resources are wasted. Summary of the Invention

[0004] This application aims to address the problems of poor accuracy and high manpower and material consumption in existing methods for simulating landslide dam failures, and proposes an experimental method and apparatus for simulating the formation and failure of landslide dams in narrow and deep valleys.

[0005] The technical solution adopted by this application to solve the above-mentioned technical problems is:

[0006] Firstly, a test method is provided to simulate the formation and failure of landslide dams in narrow and deep river valleys, the method comprising:

[0007] An experimental device is constructed, which includes at least a monitoring module, a water supply module, a river channel model, a soil sliding module, and a tailings collection module. The water supply module is connected to the tailings collection module through the river channel model and is higher than the tailings collection module. The soil sliding module is located on one side of the river channel model.

[0008] The water supply module is controlled to form an upstream flow, and soil capable of completely blocking the river channel is provided in the soil sliding module. Then, the soil in the soil sliding module is controlled to slide into the river channel model and accumulate to form a dam.

[0009] After the soil that has slid into the river channel model completely blocks the river channel, the test conditions parameters are obtained. The test conditions parameters include at least the length-to-height ratio, dam height, reservoir capacity, volume, upstream flow, and dam material.

[0010] Determine whether the landslide dam will breach under the test conditions. If so, simulate the formation and breach process of the landslide dam in the narrow and deep valley.

[0011] The monitoring module records image and experimental data during the simulated formation and collapse of a landslide dam in a narrow and deep valley.

[0012] The soil sliding module is equipped with soil capable of completely blocking the river channel, specifically including:

[0013] The landslide is generalized as an orthogonal complete blockage of the river channel. The minimum earthwork volume required for complete dam blockage is calculated using the following formula:

[0014]

[0015] Among them, V min B is the minimum earthwork volume, and H is the width of the river channel. r L is the water depth, and L is the length of the dam along the river channel. To block the internal friction angle of riverbed soil and sand materials under water-saturated conditions, The minimum slope at which debris flows occur due to blockages in a river channel;

[0016] Determine the volume of soil that slides into the riverbed per unit time, wherein the volume of soil that slides into the riverbed per unit time satisfies the following condition:

[0017]

[0018] Among them, Q s Let γ be the volume of soil sliding into the riverbed per unit time, Q be the cross-sectional flow rate per unit time, and γ be the volume of soil sliding into the riverbed per unit time. s γ represents the specific gravity of the landslide dam. w β is the specific gravity of water, and β is the riverbed slope ratio;

[0019] The composition of the soil material is determined. If the dam blockage lasts longer than the preset duration, the composition of the soil material must meet the following conditions:

[0020] U c ′>V r ;

[0021] Among them, U c V' is the starting velocity related to the minimum water depth and the dam particles. r The velocity of the upstream flow;

[0022] Based on the determined minimum earthwork volume, the volume of soil sliding into the riverbed per unit time, and the composition of the soil, the soil sliding module is equipped with soil capable of completely blocking the riverbed.

[0023] Furthermore, determining whether the landslide dam will breach under the test parameters specifically includes:

[0024] Obtain natural failure cases from the case library and the key parameters affecting the failure result corresponding to each failure case. Construct a failure prediction model based on the category of the key parameters and their corresponding failure results.

[0025] After converting the key parameters in the test conditions, the dam will be determined whether it will fail under the test conditions based on the category of the converted key parameters and the failure prediction model.

[0026] Furthermore, based on the categories of the converted key parameters and the failure prediction model, it is determined whether the landslide dam will fail under the experimental operating conditions, specifically including:

[0027] When the length-to-height ratio is greater than the first preset value or the downstream slope is less than the second preset value, if the dam material is crushed stone, boulder or large rock, it is determined that the landslide dam under the test conditions will not fail; if the dam material is fine-grained soil, it is determined that the landslide dam under the test conditions will fail.

[0028] When the length-to-height ratio is not greater than the first preset value and the downstream slope is not less than the second preset value, the category of the converted key parameters is input into the failure prediction model to obtain the failure prediction result of the landslide dam under the test conditions.

[0029] Furthermore, the key parameters include upstream flow, dam material, and reservoir capacity, and the failure prediction model is as follows:

[0030]

[0031] Where p is the probability of dam failure, x1 is the type of upstream flow, x2 is the type of dam material, and x3 is the type of reservoir capacity.

[0032] Furthermore, the water supply module includes a water storage tank, a flow control valve, and an outlet pipe. The bottom side of the water storage tank is connected to an inlet pipe, and the flow control valve is installed on the inlet pipe.

[0033] The river model is built by scaling the river topography of the landslide dam according to a preset ratio. The river model includes a water storage area and a dam accumulation area. The water storage area is connected to the water storage pool. The side wall of the dam accumulation area is equipped with scale markings. A transparent plate is placed parallel to the top of the dam accumulation area. The transparent plate is equipped with grid lines. The soil sliding module is set on the side wall of the dam accumulation area. The tailings collection module is set at the downstream end of the dam accumulation area.

[0034] The soil sliding module includes a landslide trough, a controllable hydraulic rod, a push plate, a lifting gate, and an adjustable support rod. The landslide trough is inclinedly set on the side wall of the dam's accumulation area. The adjustable support rod is set at the bottom of the landslide trough and is used to adjust the inclination angle of the landslide trough. The controllable hydraulic rod, the push plate, and the lifting gate are sequentially set in the landslide trough. The controllable hydraulic rod is used to push the push plate to the lifting gate.

[0035] The tailings collection module includes a tailwater pool and a collection box. The collection box is fixed in the tailwater pool by a connecting column. The collection box is connected to the tail end of the river model module. A filter screen is installed in the collection box. The bottom of the tailwater pool is connected to the water storage tank through a return water pipe. A filter and a water pump are installed on the return water pipe.

[0036] Furthermore, the formation and collapse process of landslide dams in narrow and deep river valleys was simulated, specifically including:

[0037] By controlling the flow control valve on the reservoir, a stable upstream flow is formed. The controllable hydraulic rod pushes the soil on the push plate to the lifting gate, and at the same time opens the lifting gate in the soil sliding module, so that the soil forms a landslide body and rushes into the river model to accumulate into a dam.

[0038] Furthermore, the monitoring module includes a first water level gauge, a second water level gauge, a propeller current meter, a first camera, a second camera, and a third camera;

[0039] The first water level gauge is mounted on a first crossbar on the upstream side of the dam accumulation area, and the second water level gauge is mounted on a second crossbar on the downstream side of the dam accumulation area. The first and second crossbars can move longitudinally along the river channel model, and the first and second water level gauges can move laterally along their respective crossbars. The propeller velocity meter is mounted on a robotic arm on the downstream side of the dam accumulation area. The robotic arm is placed on a third crossbar and can move laterally along the third crossbar. The first camera is mounted on a sliding bar at the top of the dam, the second camera is mounted directly in front of the tailings collection module, and the third camera is mounted on the opposite side wall of the dam accumulation area relative to the landslide trough.

[0040] Furthermore, the monitoring module records image and experimental data during the simulated formation and collapse of a landslide dam in a narrow, deep valley, specifically including:

[0041] Start each camera to record video, documenting the entire process of the landslide body rushing into the river channel model and accumulating into a dam, as well as the erosion process of the upstream and downstream slopes and top of the dam by the water flow;

[0042] A cross-section is selected at predetermined intervals from the upstream to the downstream side of the dam. The erosion rate of the breach width of each cross-section is calculated based on the recorded change of the breach width over time. The formula for calculating the erosion rate of the breach width is as follows:

[0043]

[0044] Where P is the erosion rate, ΔL is the change in dam size, and ΔT is the change over time;

[0045] Turn on the first and second water level gauges to monitor the water level, and calculate the outflow through the breach based on the monitored water level changes. The calculation formula is as follows:

[0046]

[0047] Where W is the reservoir capacity of the landslide dammed lake, t is time, and Q is... i For inbound traffic, Q b This refers to the outflow rate through the breach.

[0048] Secondly, a test apparatus is provided to simulate the formation and failure of a landslide dam in a narrow and deep valley. The apparatus is used to implement the test method for simulating the formation and failure of a landslide dam in a narrow and deep valley as described in the first aspect.

[0049] The beneficial effects of this application are as follows: The experimental method and apparatus for simulating the formation and failure of landslide dams in narrow and deep valleys described in this application can more realistically reproduce the formation and failure process of natural landslide dams by setting up a river channel model in the experimental apparatus, thereby improving the scientificity and accuracy of the research on the formation and failure process of dam bodies. Furthermore, this application adds a pre-judgment of whether the dam body will fail to the traditional experimental method. The landslide dam formation and failure test is only conducted when it is determined that a failure will occur. This avoids the failure of the failure test due to improper setting of parameters such as upstream flow, material composition, and geometric characteristics, which may result in the dam body failing after overtopping and making it difficult to measure the required failure parameters. This avoids the waste of manpower and material resources and improves the efficiency of the test. Attached Figure Description

[0050] Figure 1 A schematic flowchart illustrating an experimental method for simulating the formation and failure of a landslide dam in a narrow and deep valley, provided as an embodiment of this application;

[0051] Figure 2 A schematic diagram of the structure of an experimental device for simulating the formation and failure of a landslide dam in a narrow and deep valley, provided in an embodiment of this application;

[0052] Figure 3 A schematic diagram of the structure of control section #1 in a river channel model provided in this application embodiment;

[0053] Figure 4 A schematic diagram of the structure of control section #2 in a river channel model provided in this application embodiment;

[0054] Figure 5 This is a schematic diagram of the structure of a soil sliding module provided in an embodiment of this application;

[0055] Figure 6 This is a schematic diagram of the structure of a material collection box provided in an embodiment of this application;

[0056] Figure 7 A schematic diagram of a landslide completely blocked as provided in an embodiment of this application;

[0057] Figure 8 A schematic diagram of the geometric parameters of a dam body provided for an embodiment of this application;

[0058] Explanation of reference numerals in the attached figures:

[0059] 1-Water storage tank, 2-Flow control valve, 3-Outlet pipe, 4-Water storage area, 5-Dam accumulation area, 6-Transparent panel, 7-First crossbar, 8-Third crossbar, 9-Second crossbar, 11-Robotic arm, 10-First water level gauge, 12-Second water level gauge, 13-Third camera, 14-Second camera, 15-Collection box, 16-Tailwell tank, 17-Return water pipe, 18-Filter, 19-Water pump, 20-Landslide trough, 21-Push plate, 22-Lifting gate, 23-Adjustable support rod, 24-Hydraulic rod, 25-Electric lock, 26-Filter screen, 27-Flow meter. Detailed Implementation

[0060] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings.

[0061] In some of the processes described in the specification and accompanying drawings of this application, multiple operations appear in a specific order. However, it should be clearly understood that these operations may not be executed in the order they appear herein, or they may be executed in parallel. The operation numbers, such as 101, 102, etc., are merely used to distinguish different operations and do not represent any execution order. Furthermore, these processes may include more or fewer operations, and these operations may be executed sequentially or in parallel. It should be noted that the descriptions such as "first," "second," etc., in this document are used to distinguish different messages, devices, modules, etc., and do not represent a chronological order, nor do they limit "first" and "second" to different types.

[0062] The technical solutions of this application are applicable to application scenarios that require simulating the formation and collapse of landslide dams in narrow and deep valleys, such as "V" shaped valley terrain.

[0063] Please see Figure 1 The experimental method for simulating the formation and failure of landslide dams in narrow and deep valleys, as described in this application embodiment, includes the following steps:

[0064] Step 101: Construct an experimental device, which includes at least a monitoring module, a water supply module, a river channel model, a soil sliding module, and a tailings collection module. The water supply module is connected to the tailings collection module through the river channel model. The water supply module is higher than the tailings collection module. The soil sliding module is located on one side of the river channel model.

[0065] In practical applications, the valley parameters of the narrow, deep valley to be simulated can be scaled up to a certain ratio to construct the experimental setup. Please refer to [link / reference]. Figure 2The experimental setup mainly consists of a monitoring module, a water supply module, a river channel model module, a soil sliding module, and a tailings collection module. The river channel model connects the water supply module and the tailings collection module, with the water supply module positioned higher than the tailings collection module to ensure a stable water flow. The soil sliding module is located on one side of the river channel model, facilitating the pushing of fully mixed multi-graded soil into the model. The tailings collection module can collect residual dam material and water after the screening test.

[0066] In this embodiment of the application, the water supply module includes a water storage tank 1, a flow control valve 2, and an outlet pipe 3. The bottom side of the water storage tank 1 is connected to an inlet pipe. The flow control valve 2 is installed on the inlet pipe. By adjusting the opening of the flow control valve 2, the flow rate injected into the water storage tank 1 can be controlled, and the flow rate can be ensured to be stable.

[0067] In this embodiment, the river channel model is established by scaling the river channel topography at a preset scale based on the location of the landslide dam. For example, when referring to the cross-sectional topography of the Baige landslide dam location, and selecting the river channel from 1.5km upstream to 2km downstream of the dam, and establishing the model at a horizontal flow scale of 1:200, it includes 18 control sections, among which control sections #1 and #2 are as follows: Figure 3 and Figure 4 As shown, the other cross-sections are similar.

[0068] The river model includes a water storage area 4 and a dam accumulation area 5. The water storage area 4 is connected to the water storage tank 1. The side wall of the dam accumulation area 5 is equipped with scale markings. A transparent plate 6 is placed parallel to the top of the dam accumulation area 5. The transparent plate 6 is equipped with grid lines. The soil sliding module is set on the side wall of the dam accumulation area 5. The tailings collection module is set at the downstream end of the dam accumulation area 5.

[0069] In this embodiment, the side walls of the river model are made of transparent PVC soft board, and the bottom of the river model is fitted with corresponding water release sealing strips. Scale markings are set inside the side walls of the dam body accumulation area 5. The scale markings are used to measure and observe the vertical downward erosion process of the breach. A transparent plate 6 with a 10cm*10cm grid area is placed parallel to the top of the dam body accumulation area 5. The transparent plate 6 is used to measure and observe the lateral widening process of the breach, which can more accurately obtain the geometric changes of each section when the dam body collapses, and digitize the dam failure process.

[0070] In this embodiment, the soil sliding module includes a landslide trough 20, a controllable hydraulic rod 24, a push plate 21, a lifting gate 22, and an adjustable support rod 23. The landslide trough 20 is inclinedly disposed on the side wall of the dam accumulation area 5. The adjustable support rod 23 is disposed at the bottom of the landslide trough 20 and is used to adjust the inclination angle of the landslide trough 20 to meet different test conditions. The controllable hydraulic rod 24, the push plate 21, and the lifting gate 22 are sequentially disposed in the landslide trough 20. The controllable hydraulic rod 24 is used to push the push plate 21 to the lifting gate 22.

[0071] Please see Figure 5 In practical applications, a strip plate is provided on the side wall of the landslide trough 20, with several through holes evenly distributed on the strip plate. An electric bolt lock 25 is provided on the side of the push plate 21. The bolt of the electric bolt lock 25 can match the through holes, and the electric bolt lock 25 is connected to a switch controller to facilitate the control of the extension and retraction of the bolt. The pushing parts are several evenly distributed controllable hydraulic rods 24. The controllable hydraulic rods 24 can push the push plate 21 to the lifting gate 22. The thrust of the controllable hydraulic rods 24 on the push plate 21 provides kinetic energy for the sliding of soil and rock materials, thereby giving the sliding soil and rock materials different initial velocities. Prepared soil and rock materials are placed between the push plate 21 and the lifting gate 22 of the landslide trough 20. They slide out through the lifting gate 22 and slide down the river channel side wall of the dam accumulation area 5 to the bottom of the river channel model, simulating the process of landslide dam formation in a narrow and deep valley, which is closer to the real situation.

[0072] In this embodiment, the tailings collection module includes a tailwater pool 16 and a collection box 15. The collection box 15 is fixed inside the tailwater pool 16 by a connecting column. The collection box 15 is connected to the tail end of the river model module. A filter screen 26 is installed inside the collection box 15. Please refer to [link to relevant documentation]. Figure 6 In this embodiment of the application, the filter screen 26 can be two or three layers of filter screen that can separate the boulders, crushed stones and gravel in the dam material. The bottom of the tailrace pool 16 is connected to the reservoir 1 through the return water pipe 17. The return water pipe 17 is equipped with a filter 18 and a water pump 19 to circulate water to the upstream reservoir 1 and save water.

[0073] In this embodiment of the application, the monitoring module includes a first water level meter 10, a second water level meter 12, a propeller current meter 27, a first camera (not shown in the figure), a second camera 14, and a third camera 13;

[0074] The first water level gauge 10 is mounted on the first crossbar 7 on the upstream side of the dam accumulation area 5, and the second water level gauge 12 is mounted on the second crossbar 9 on the downstream side of the dam accumulation area 5. The first crossbar 7 and the second crossbar 9 can move longitudinally along the river channel model, and the first water level gauge 10 and the second water level gauge 12 can move laterally along the corresponding crossbars. The propeller velocity meter 27 is mounted on the robotic arm 11 on the downstream side of the dam accumulation area 5. The robotic arm 11 is placed on the third crossbar 8. The robotic arm 11 can be automatically moved laterally along the crossbar 8 by a motor, which can control the lateral movement of the velocity meter 27. The robotic arm 11 is equipped with a sensor device. When large particles of silt are detected in the downstream water flow, the propeller velocity meter 27 will be automatically lifted to protect the propeller.

[0075] The first camera is mounted on a sliding rod at the top of the dam, specifically using a tripod. The camera's position can be adjusted by changing the position of the sliding rod and the tripod. Specifically, the camera at the top of the dam is slidably connected to the sliding rod, and a bolt can be used to fix the first camera to a position where the thread of the bolt matches the thread of the corresponding sliding rod. This threaded engagement allows the bolt to move the first camera along its corresponding sliding rod, adjusting the camera's position horizontally and vertically to achieve the optimal shooting position. The second camera 14 is mounted directly in front of the tailings collection module. The second camera 14 records the dam failure pattern and the development process of the breach at each stage from the downstream side. The third camera 13 is mounted on the opposite sidewall of the dam's accumulation area 5 relative to the landslide trough 20, used to record the changes in the dam's failure morphology from the side.

[0076] Step 102: Control the water supply module to form an upstream flow, and equip the soil sliding module with soil that can completely block the river channel. Then control the soil in the soil sliding module to slide into the river channel model and accumulate to form a dam.

[0077] Please see Figure 7 In this embodiment of the application, after the upstream flow is formed, the landslide is generalized as an orthogonal complete blockage of the river channel, and soil material capable of completely blocking the river channel is provided in the following manner:

[0078] Step 1021: Calculate the minimum earthwork volume required for complete dam sealing. The calculation formula is as follows:

[0079]

[0080] Among them, V min B is the minimum earthwork volume, and H is the width of the river channel. r Let L be the water depth and L be the length of the dam along the river channel. Here, L = nB, where n is a value between 3 and 4. To block the internal friction angle of riverbed soil and sand materials under water-saturated conditions, The minimum slope at which debris flows occur due to blockages in a river channel;

[0081] Step 1022: Determine the volume of soil that slides into the riverbed per unit time, wherein the volume of soil that slides into the riverbed per unit time satisfies the following condition:

[0082]

[0083] Among them, Q s Let γ be the volume of soil sliding into the riverbed per unit time, Q be the cross-sectional flow rate per unit time, and γ be the volume of soil sliding into the riverbed per unit time. s γ represents the specific gravity of the landslide dam. w β is the specific gravity of water, and β is the riverbed slope ratio;

[0084] Step 1023: Determine the composition of the soil. If the dam blockage lasts longer than the preset duration, the composition of the soil must meet the following conditions:

[0085] U c ′>V r ;

[0086] Among them, U c V' is the starting velocity related to the minimum water depth and the dam particles. r The velocity of the upstream flow;

[0087] Step 1024: Based on the determined minimum earthwork volume, the volume of soil sliding into the riverbed per unit time, and the composition of the soil, prepare soil in the soil sliding module that can completely block the riverbed.

[0088] Based on the minimum earthwork volume required for complete dam blockage, the volume of soil sliding into the river channel per unit time, and its material composition, soil is prepared in the soil sliding module to ensure that the river channel can be completely blocked in one operation. Then, the soil in the soil sliding module is controlled to rush into the river channel model and accumulate into a dam body.

[0089] Step 103: After the soil that has slid into the river channel model completely blocks the river channel, obtain the test conditions parameters. The test conditions parameters include at least the length-to-height ratio, dam height, reservoir capacity, volume, upstream flow, and dam material.

[0090] The test parameters include the valley parameters of the narrow and deep valley to be simulated, as well as the test parameters used to simulate the formation and failure of landslide dams.

[0091] Step 104: Determine whether the landslide dam will breach under the test conditions. If so, simulate the formation and breach process of the landslide dam in the narrow and deep valley.

[0092] In this embodiment of the application, determining whether a landslide dam will breach under the test conditions specifically includes:

[0093] Step 1041: Obtain natural failure cases from the case library and the key parameters affecting the failure results corresponding to each failure case; construct a failure prediction model based on the categories of the key parameters and their corresponding failure results.

[0094] In practical applications, we can select 49 landslide dam cases from 1654 to the present with detailed information that were not solely caused by human destruction, as shown in the table below:

[0095]

[0096]

[0097] This application embodiment constructs a failure prediction model based on the data in the table above, specifically including the following steps:

[0098] (1) Classification of geometric parameters of landslide dams and lake parameters; please refer to the dam mass parameters section. Figure 8 The parameters such as dam height H, reservoir capacity W, volume V, upstream flow Q, and dam length-to-height ratio L / H are classified into categories III (3) or IV (4). (The dam height after treatment is the default dam height at the pass, and the volume and reservoir capacity are the values ​​after treatment. The volume is based on the reservoir capacity classification value.) To maximize the use of existing data, the case data in Table 1 were classified and processed as follows: ① For dams where accurate upstream flow values ​​were not collected, upstream flow was classified as I(1) when the recorded data described it as "extremely small upstream flow", "even if it overflows, the upstream flow has no scouring force", "extremely arid river", and "annual average flow is much smaller than the I(1) flow classification standard value"; ② Cases described as "experiencing a flood season", "large inflow, quickly scouring away", and those containing descriptions of "heavy rainfall", "snow melting", and "other landslide dams breaching upstream" were all classified as IV(4); ③ For the Yanchi River and Mangkang Jingshan landslide dams, the upstream flow was described as "dry season, small upstream flow". From the case records, it can be determined that the upstream flow was 56-85m greater than that of the high-risk Tangjiashan landslide dam. 3 / s(III(3)) is small, but due to the "extremely small" situation in non-I(1) class, the flow rate is assigned to class II(2); ④ For some dams that naturally collapsed after treatment (excluding artificially induced dam damage), the dams after treatment are regarded as "new dams" and reclassified according to the treatment situation. If the data is incomplete, and it is determined that the treatment will not cause changes in the dam parameters, the data category before treatment shall prevail. The classification results are shown in the table below:

[0099]

[0100] (2) The main materials of the dam body are divided into categories I(1), II(2), III(3), IV(4), and V(5) according to the fine-grained group (clay, loess), sand-soil mixture (sand is the main component), crushed stone, gravel, sand (gravel and crushed stone is the main component), block crushed stone (particle size d < 200 mm), and boulders / large boulders (particle size d is in meters) (see Table 1).

[0101] (3) Record the failure status of landslide dam events, and divide whether the failure occurred into two categories: failure and failure. Use contingency cross analysis, Kendall correlation analysis and Logistic regression analysis to conduct case statistical analysis.

[0102] (4) The key parameters for determining the dam failure include upstream inflow (positively correlated), (post-treatment) reservoir capacity (positively correlated), and dam material, as shown in the table below:

[0103]

[0104] Note: ***, **, and * represent significance levels of 1%, 5%, and 10%, respectively; "+" indicates a positive correlation, and "-" indicates a negative correlation.

[0105] (5) Based on case studies of landslides, the length-to-height ratio was determined to have an impact on whether a landslide would occur. The statistical analysis failed to characterize this impact because: ① The influence of the length-to-height ratio is mainly reflected in the downstream slope ratio, but there is limited data on downstream slope ratio cases, and most landslide dams have wide and gentle cross-sections, making differentiation difficult. ② The direct impact of the length-to-height ratio on whether a landslide would occur is only reflected in dam bodies composed of Class IV and V materials; the key factor remains the incoming flow. In actual cases, such as the Caoling landslide dam which collapsed due to heavy rain, its length-to-height ratio reached 83%, the dam body material was mainly boulders, and the subsequent upstream flow was very small, thus preventing a collapse. However, for debris flow-type landslide dams such as Yigong, although the dam slope is wide and gentle, the dam body is composed of fine particles, and it still collapsed after the water overflowed the top.

[0106] Based on this, this application embodiment, for cases where the length-to-height ratio is not greater than a first preset value and the downstream slope is not less than a second preset value, obtains a breakdown prediction model based on logistic regression model training, as follows:

[0107]

[0108] Where p is the probability of dam failure, x1 is the type of upstream flow, x2 is the type of dam material, and x3 is the type of reservoir capacity.

[0109] The existing case studies fully encompass the above parameter information. The model was derived using 34 cases (80%) and validated using 8 cases (20%). The model accuracy was 91.2%, and the likelihood ratio chi-squared value was 17.612 (p = 0.000***), indicating statistical significance and predictive effectiveness. Only one of the 8 cases used for validation resulted in a prediction error, achieving an accuracy rate of 87.5%, demonstrating that this logistic regression model for dam failure can be used to predict whether a dam will fail.

[0110] Step 1042: After converting the key parameters in the test conditions parameters, determine whether the landslide dam will breach under the test conditions parameters based on the category of the converted key parameters and the breach prediction model.

[0111] After obtaining the failure prediction model, it can be determined whether the landslide dam will fail under the test conditions. In this embodiment, the converted key parameters can be classified using the same method as described above, and failure prediction can be performed based on the category of the converted key parameters. Specifically, this includes:

[0112] When the length-to-height ratio is greater than the first preset value or the downstream slope is less than the second preset value, if the dam material is crushed stone, boulders, or large rocks, it is determined that the landslide dam under the test conditions will not fail. If the dam material is fine-grained soil, it is determined that the landslide dam under the test conditions will fail. For dams with a large length-to-height ratio (Class III) or a gentle downstream slope, and mainly composed of Class IV or V materials with strong erosion resistance, if the upstream inflow is Class I, the water flow is unlikely to overflow the dam due to the balance between seepage and inflow, and even if it overflows, it will not fail. For dams with a large length-to-height ratio (Class III) or a gentle downstream slope, and mainly composed of Class I materials with extremely poor erosion resistance, failure will definitely occur as long as the water level of the upstream landslide dam lake continues to rise.

[0113] When the length-to-height ratio is not greater than the first preset value and the downstream slope is not less than the second preset value, the category of the converted key parameters is input into the failure prediction model, and the failure prediction result of the landslide dam under the test conditions can be obtained.

[0114] Once it is determined that the landslide dam will fail under the current simulated operating parameters, the landslide dam formation and failure test can begin. Based on the aforementioned test setup, the simulation process mainly includes:

[0115] First, by controlling the flow control valve 2 on the reservoir 1, a stable upstream flow is formed, and a certain amount of soil is prepared in advance at the push plate 21 according to the volume of the dam body after conversion based on the water flow ratio; then, the controllable hydraulic rod 24 is controlled to push the soil on the push plate 21 to the lifting gate 22, and at the same time, the lifting gate 22 in the soil sliding module is opened, so that the soil forms a landslide body and rushes into the river model to accumulate into a dam body.

[0116] Step 105: Record image and experimental data during the simulated formation and collapse of a landslide dam in a narrow and deep valley using the monitoring module.

[0117] Specifically, while performing the above procedures, each camera is activated to record video, documenting the entire process of the landslide body rushing into the river channel model and accumulating into a dam, as well as the erosion process of the upstream and downstream slopes and top of the dam by the water flow.

[0118] During the breach of a landslide dam, the water and sediment interactions vary significantly across different parts of the breach, leading to different breach widening processes. Therefore, the interaction between widening and flow is a continuous process; studying only a single cross-section is insufficient, failing to reflect the overall breach widening process and affecting the accuracy of breach flow calculations. Based on this, in this embodiment, six typical cross-sections are selected at 10cm intervals from the upstream to the downstream side of the dam. To further analyze the entire breach widening process, the breach width at different locations and time points during the sequential breach is recorded, showing the change in breach width over time, the change in breach width per unit time, and the breach widening erosion rate. The breach widening erosion rates of the six typical cross-sections from the upstream to the downstream side of the dam are calculated sequentially. This allows for the summarization of the time-dependent distribution of the widening erosion rate at the same cross-section and the longitudinal distribution of the widening erosion rate at different cross-sections, deepening the understanding of the entire breach widening process and the characteristics of longitudinal morphological changes under the overtopping failure of a landslide dam.

[0119] Taking the section at the middle of the dam as an example, the calculation of the erosion rate of the breach widening is explained as follows:

[0120] By observing the development of the breach at the top of the dam using a transparent plate with grid lines (6) and the changes in breach time in video footage recorded by cameras, the erosion rate at the top of the breach can be obtained.

[0121]

[0122] Where P is the erosion rate, ΔL is the change in dam size, and ΔT is the change over time.

[0123] Simultaneously with the above process, the first water level gauge 10 and the second water level gauge 12 are activated to record the downstream water level changes during the upstream rise and dam breach processes. During dam breach, the breach discharge is a crucial parameter, but it is often difficult to measure directly. In this embodiment, the breach discharge is calculated indirectly by measuring upstream water level changes using the reservoir balance principle. The calculation formula is as follows:

[0124]

[0125] Where W is the reservoir capacity of the landslide dammed lake, t is time, and Q is... iFor inbound traffic, Q b This refers to the outflow rate through the breach.

[0126] In practical applications, the tilt angle of the landslide trough 20, the fixed position of the push plate 21, the upstream flow rate, and the composition of the dam material can be adjusted. The above steps can be repeated multiple times to obtain images and data of the formation and failure process of the landslide dam under various working conditions, and the test results can be compared and analyzed.

[0127] In summary, the experimental method for simulating the formation and failure of landslide dams in narrow and deep valleys described in this application references the characteristic that typical landslide dams often occur in narrow and deep river channels. It takes into account the influence of deep "V" topography on dam failure simulation and the natural stacking process of dam formation. This method can more realistically reproduce the formation and failure process of natural landslide dams, improving the scientific rigor and accuracy of dam formation and failure process research. The grid lines on the top and sides of the dam can more accurately obtain the development of the breach morphology of each dam section during the failure process, making the dam failure process data-driven. The tailings collection device can perform preliminary screening of the dam material in the downstream water flow, facilitating the analysis and reuse of the particle size distribution of the residual soil and rock after the dam failure. At the same time, water can be saved by recycling water through the return water pipe. In addition, in terms of experimental methods and procedures, it is considered that landslide dams are different from traditional earth-rock dams, as they are composed of uneven soil and rock particles, and the upstream and downstream dam slopes are mainly gentle slopes. When the upstream flow is small, if the dam body is composed of highly permeable materials, the upstream and downstream flows remain balanced due to dam seepage, and the upstream landslide dam enters a relatively stable period, thus preventing dam failure. Alternatively, if the dam body is composed of highly erosion-resistant materials, when the breach coarsens to a certain extent during headward erosion, and the upstream flow is small and the dam slope is gentle, it is difficult to form continuous erosion, preventing dam failure. To avoid improper setting of parameters such as upstream flow, material composition, and geometric characteristics that affect dam failure, leading to failure even after overtopping and difficulty in measuring the required failure parameters, this invention supplements traditional experimental methods with an effective method for rapid pre-determination of dam failure. Furthermore, this method for determining dam failure maximizes the use of landslide dam case data over a long span and, compared with existing research, considers the impact of treatment measures on the geometric parameters of the landslide dam and the lake parameters. The above-mentioned experimental device and method can be widely applied to simulation experiments of landslide dam blockage and failure in narrow and deep river channels.

[0128] Based on the above technical solution, this application also proposes an experimental device for simulating the formation and collapse of landslide dams in narrow and deep valleys. The device is characterized in that it is used to implement the experimental method for simulating the formation and collapse of landslide dams in narrow and deep valleys as described in the embodiments.

[0129] It is understood that since the experimental apparatus for simulating the formation and failure of landslide dams in narrow and deep valleys described in the embodiments of the present invention is an apparatus for implementing the experimental method for simulating the formation and failure of landslide dams in narrow and deep valleys as described in the embodiments, the apparatus disclosed in the embodiments is relatively simple to describe since it corresponds to the method disclosed in the embodiments. For relevant parts, please refer to the description of the method, and it will not be repeated here.

Claims

1. A test method for simulating the formation and failure of landslide dams in narrow and deep river valleys, characterized in that, The method includes: An experimental device is constructed, which includes at least a monitoring module, a water supply module, a river channel model, a soil sliding module, and a tailings collection module. The water supply module is connected to the tailings collection module through the river channel model and is higher than the tailings collection module. The soil sliding module is located on one side of the river channel model. The water supply module is controlled to form an upstream flow, and soil capable of completely blocking the river channel is provided in the soil sliding module. Then, the soil in the soil sliding module is controlled to slide into the river channel model and accumulate to form a dam. After the soil that has slid into the river channel model completely blocks the river channel, the test conditions parameters are obtained. The test conditions parameters include at least the length-to-height ratio, dam height, reservoir capacity, volume, upstream flow, and dam material. Determine whether the landslide dam will breach under the test conditions. If so, simulate the formation and breach process of the landslide dam in the narrow and deep valley. The monitoring module records image and experimental data during the simulated formation and collapse of a landslide dam in a narrow and deep valley. The soil sliding module is equipped with soil capable of completely blocking the river channel, specifically including: The landslide is generalized as an orthogonal complete blockage of the river channel. The minimum earthwork volume required for complete dam blockage is calculated using the following formula: ； in, Minimum earthwork volume The width of the river channel, Because of the water depth, The length of the dam along the river channel. To block the internal friction angle of riverbed soil and sand materials under water-saturated conditions, The minimum slope at which debris flows occur due to blockages in a river channel; Determine the volume of soil that slides into the riverbed per unit time, wherein the volume of soil that slides into the riverbed per unit time satisfies the following condition: ； in, This refers to the volume of soil that slides into the riverbed per unit time. The cross-sectional inflow rate per unit time. The specific gravity of the landslide dam is... The density of water, Riverbed slope ratio; The composition of the soil material is determined. If the dam blockage lasts longer than the preset duration, the composition of the soil material must meet the following conditions: ； in, The starting flow velocity is related to the minimum water depth and the dam body particles. The velocity of the upstream flow; Based on the determined minimum earthwork volume, the volume of soil sliding into the riverbed per unit time, and the composition of the soil, the soil sliding module is equipped with soil capable of completely blocking the riverbed. Determining whether the landslide dam will breach under the test conditions specifically includes: Obtain natural failure cases from the case library and the key parameters affecting the failure result corresponding to each failure case. Construct a failure prediction model based on the category of the key parameters and their corresponding failure results. After converting the key parameters in the test conditions, the dam's potential failure under the test conditions is determined based on the category of the converted key parameters and the failure prediction model; specifically including: When the length-to-height ratio is greater than the first preset value or the downstream slope is less than the second preset value, if the dam material is crushed stone, boulder or large rock, it is determined that the landslide dam under the test conditions will not fail; if the dam material is fine-grained soil, it is determined that the landslide dam under the test conditions will fail. When the length-to-height ratio is not greater than the first preset value and the downstream slope is not less than the second preset value, the category of the converted key parameters is input into the failure prediction model to obtain the failure prediction result of the landslide dam under the test conditions. The key parameters include upstream inflow, dam material, and reservoir capacity. The failure prediction model is as follows: ； in, The probability of dam failure. The category of upstream flow. The type of dam material, This refers to the category of storage capacity.

2. The experimental method for simulating the formation and failure of landslide dams in narrow and deep valleys according to claim 1, characterized in that, The water supply module includes a water storage tank, a flow control valve, and an outlet pipe. The bottom side of the water storage tank is connected to an inlet pipe, and the flow control valve is installed on the inlet pipe. The river model is built by scaling the river topography of the landslide dam according to a preset ratio. The river model includes a water storage area and a dam accumulation area. The water storage area is connected to the water storage pool. The side wall of the dam accumulation area is equipped with scale markings. A transparent plate is placed parallel to the top of the dam accumulation area. The transparent plate is equipped with grid lines. The soil sliding module is set on the side wall of the dam accumulation area. The tailings collection module is set at the downstream end of the dam accumulation area. The soil sliding module includes a landslide trough, a controllable hydraulic rod, a push plate, a lifting gate, and an adjustable support rod. The landslide trough is inclinedly set on the side wall of the dam's accumulation area. The adjustable support rod is set at the bottom of the landslide trough and is used to adjust the inclination angle of the landslide trough. The controllable hydraulic rod, the push plate, and the lifting gate are arranged sequentially in the landslide trough. The controllable hydraulic rod is used to push the push plate to the lifting gate. The tailings collection module includes a tailwater pool and a collection box. The collection box is fixed in the tailwater pool by a connecting column. The collection box is connected to the tail end of the river model module. A filter screen is installed in the collection box. The bottom of the tailwater pool is connected to the water storage tank through a return water pipe. A filter and a water pump are installed on the return water pipe.

3. The experimental method for simulating the formation and failure of landslide dams in narrow and deep valleys according to claim 2, characterized in that, Simulating the formation and collapse process of landslide dams in narrow and deep river valleys, specifically including: By controlling the flow control valve on the reservoir, a stable upstream flow is formed. The controllable hydraulic rod pushes the soil on the push plate to the lifting gate, and at the same time opens the lifting gate in the soil sliding module, so that the soil forms a landslide body and rushes into the river model to accumulate into a dam.

4. The experimental method for simulating the formation and failure of landslide dams in narrow and deep valleys according to claim 2, characterized in that, The monitoring module includes a first water level gauge, a second water level gauge, a propeller current meter, a first camera, a second camera, and a third camera; The first water level gauge is mounted on a first crossbar on the upstream side of the dam accumulation area, and the second water level gauge is mounted on a second crossbar on the downstream side of the dam accumulation area. The first and second crossbars can move longitudinally along the river channel model, and the first and second water level gauges can move laterally along their respective crossbars. The propeller velocity meter is mounted on a robotic arm on the downstream side of the dam accumulation area. The robotic arm is placed on a third crossbar and can move laterally along the third crossbar. The first camera is mounted on a sliding bar at the top of the dam, the second camera is mounted directly in front of the tailings collection module, and the third camera is mounted on the opposite side wall of the dam accumulation area relative to the landslide trough.

5. The experimental method for simulating the formation and failure of landslide dams in narrow and deep valleys according to claim 4, characterized in that, The monitoring module records image and experimental data during the simulated formation and collapse of a landslide dam in a narrow, deep valley, specifically including: Start each camera to record video, documenting the entire process of the landslide body rushing into the river channel model and accumulating into a dam, as well as the erosion process of the upstream and downstream slopes and top of the dam by the water flow; A cross-section is selected at predetermined intervals from the upstream to the downstream side of the dam. The erosion rate of the breach width of each cross-section is calculated based on the recorded change of the breach width over time. The formula for calculating the erosion rate of the breach width is as follows: ； in, For the erosion rate, Due to changes in dam dimensions, For changes over time; Turn on the first and second water level gauges to monitor the water level, and calculate the outflow through the breach based on the monitored water level changes. The calculation formula is as follows: ； in, For the reservoir capacity of the landslide dammed lake, For time, For inbound flow, This refers to the outflow rate through the breach.

6. An experimental apparatus for simulating the formation and failure of landslide dams in narrow and deep river valleys, characterized in that, The apparatus is used to implement the experimental method for simulating the formation and failure of landslide dams in narrow and deep valleys as described in any one of claims 1 to 5.

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